Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1989 Stratigraphy and Sedimentology of Holocene Overbank Deposits of the Mississippi River, False River Region, Louisiana. Kathleen Marie Farrell Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Farrell, Kathleen Marie, "Stratigraphy and Sedimentology of Holocene Overbank Deposits of the Mississippi River, False River Region, Louisiana." (1989). LSU Historical Dissertations and Theses. 4776. https://digitalcommons.lsu.edu/gradschool_disstheses/4776 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. 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University Microfilms International A Hen ft HnvVf'M Information C om pany tOO North/net) Rond Ann Art tor M148100 1840 USA 0U /tit 4/00 800 O'M 0000 Order Number 9017260 Stratigraphy and sedimentology of Holocene overbank deposits of the Mississippi River, False River region, Louisiana Farrell, Kathleen Marie, Ph.D. The Louisiana State University and Agricultural and Mechanical Col., 1989 Copyright ©1990 by Farrell, Kathleen Marie. All righta reserved. UMI 300 N. Zceb Rd. Ann Aibor, MI 48106 STRATIGRAPHY AND SEDIHENTOLOGY OF HOLOCFNE OVERBANK DEPOSITS OF THE MISSISSIPPI RIVER, FALSE RIVER REGION, LOUISIANA A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Geology and Geophysics by Kathleen Marie Farrell B.S., University of Rochester, 1976 M.A., Virginia Institute of Marine Science, 1980 August 1989 ACKNOWLEDGEMENTS A large number of individuals, funding agencies and oil companies contributed to this research effort. The late Dr. Bob Miller allowed me to use the Louisiana State University Agronomy Department's drilling rig to collect the cores through the overbank deposits. Dag Numme^al acted as committee chairman and provided career guidance. Indra Singh and Steve Johansen critically examined my research periodically. Don Lowe, Jim Coleman, Gary Byerly and Jeff Hanor served as committee members. Norm Smith, Phil Lowry and Bob Tye provided additional discussion. Clyde Moore, Art Schultz and Craig Shipp provided moral support. Funding for field, laboratory and travel expenses was acquired from the Geological Society of America (R.K. Fahnestock Award in Fluvial Sedimentology), SOHIO Petroleum Company (through L.S.U. alumnus. Norm Rosen), Arco Oil and Gas Company, Union Oil of California (UNOCAL), the Gulf Coast Association of Geological Societies, the Gulf Coast Section of the Society of Economic Paleontologists and Mineralogists, the Shell Foundation and the Louisiana State University Department of Geology. The landowners of Point Coupee Parish, especially R.L. Bergeron, were very generous in allowing access to their property. A special thanks to Bruce Lindsay who was personally responsible for operating the Giddings Rig and collecting a major portion of the field data. Numerous other individuals assisted in the collection of field data including Bryant Hinton, Riley Milner, Jason Darby and Scott Jeffrey. Danny Peace. Mary Lee Eggart, Cliff Duplechin and Joyce Nelson allowed me unlimited use of their facilities and space. ii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS 11 TABLE OF CONTENTS iii LIST OF FIGURES vlii ABSTRACT xiii CHAPTER 1. INTRODUCTION 1 CHAPTER 2. QUATERNARY GEOLOGY OF THE LONER MISSISSIPPI VALLEY 9 GEOLOGIC HISTORY 9 GEOHORPHOLOGY 13 Distribution of Environments 13 Levee and Backseamp 16 Crevasse Splays 17 Point Bar 18 Concave Bench Deposits 21 Meandering History 24 CHAPTER 3. SAMPLING 28 INTRODUCTION 28 CORING NITH A GIDDINGS RIG 28 VIBRACORING 28 CORE PREPARATION 29 X-RAY RADIOGRAPHY 30 CORE DESCRIPTION 30 CHAPTER 4. STRATIGRAPHY OF MEANDER BELT DEPOSITS 31 POINT BAR DEPOSITS 31 The Fining-Upward Sequence 31 Large-Scale Trough Cross-Stratified Sand— 31 iii Large-Scale Planar Cross-Laminated Sand— 34 Smai1-Scale Cross-Laminated Sand— 34 Upper Point Bar Deposits 34 Ripple-Drift Cross-Stratified Sand 36 Parallel Laminated Sand 46 Small-Scale Cross-Laminated Sand 47 Genesis of Lower Point Bar Deposits 47 Genesis of Upper Point Bar Deposits 50 CONCAVE BENCH DEPOSITS 53 Distribution of Units 53 Swale Fill Units 55 CB1 55 CB2 58 CB3 61 Bench Margin Deposit 61 CB4 61 Ridge Deposits 67 CB5 67 Interpretation 70 CB5 70 CB4 73 CB1 74 CB2 75 CBS 76 CHAPTER 5. FLOOD BASIN STRATIGRAPHY 79 INTRODUCTION 79 SEDIHENTOLOGY OF SHEET FLOOD DEPOSITS 79 iv Rhythmites 81 Sandy Rhythmites— 81 Silty Rhythmites— 89 Graded Rhythmites— 94 Laminates-- 94 Pelletal Fabric 94 Pelletal Silt— 97 Pelletal Sand— 98 Pelletal Hud and Clay— 98 Origin of Burrowed Fabric 98 Interpretation of Stratification 100 Factors Controlling Stratification— 100 Proximality Trends— 101 The Effect of Flow Regime— 102 Topography, Burrowing and Proximity to Source— 106 Graded Rhythmites— 107 Contacts Between Layers— 107 Recognition of Flood Events— 107 Other Bioturbation Structures 108 Root Burrowed Silt— 108 Dwelling Burrows— 108 Root Structures and Organic Material— 108 Summary of Bedding Types- 112 STRATIGRAPHY 114 Units 114 Backswamp 114 FBI— Dark Blue Clay-- 114 v FB2— Very Fine Sandy Clayey Silt— 119 FB3— Mudball Conglomerate-- 119 FB4— Rooted Clay— 120 Levee and Splay Lobe 123 FB5—Burrowed Silty Clay— 123 FB6— Rhythmically Layered Silt— 123 FB7— Pelletal Silt— 123 FB8— Dark Brown Pelletal Hud-- 124 FB9— Rhythmically Layered Sand, Silt and Clay— 124 Crevasse Channel Fill 127 CV1— Laminated Hud with Plant Debris— 127 CV2— Laminated Silt with Leaf Layers— 127 CV3—Laminated Sand— 135 CV4— Interbedded Clay and Sand— 135 CV5—Hottled Huddy Sand-- 136 DISTRIBUTION OF UNITS 136 Backswamp— 136 Levee— 137 Splay Lobe— 137 Crevasse Channel Fill— 139 INTERPRETATION OF SEQUENCES 142 Backswamp 142 Pre-Avulsion Sequence— 142 Avulsion Sequence— 143 Progradational Sequence— 143 Flood Events— 144 Sequence Summary— 144 vi Levee and Splay Lobe 145 Pre-Avulsion Sequence-- 145 Progradational Sequences— 146 Vertical Variation in Progradational Sequences— 150 1-4 H Thick Sequences— 152 Smaller-Scale Sequences— 154 Differentiating Levee and Splay Lobe Deposits 156 Crevasse Channel Fill Sequence 157 CV1-- 157 CV2— 158 CV3— 158 CV4— 159 CV5— 159 Summary of Major Events in Flood Basin Evolution 159 Pre-Avulsion Stage— 159 Avulsion Stage— 159 Early Meander Belt Stage— 162 Fully Developed Meander Belt Stage— 163 CHAPTER 6. DISCUSSION 165 CHAPTER 7. CONCLUSIONS 181 BIBLIOGRAPHY 187 APPENDIX A: TOPOGRAPHIC MAPS SHOWING CORE LOCATIONS 197 APPENDIX B: KEY TO UNITS IN CORE LOGS 201 APPENDIX C: KEY TO SYMBOLS IN CORE LOGS 202 APPENDIX D: CORE LOGS 203 VITA 345 vii LIST OF FIGURES FIGURE PAGE 1 Location of the False River Region, Solitude Point and 7 Thomas Point with respect to the Lower Mississippi Valley. Profile X-X' is shown in Fig. 3. 2 Location of the False River Region with respect to the 8 presently occupied meander belt of the Mississippi River. Fault traces are from Saucier, 1969. 3 Cross-section through the Lower Mississippi Valley. 10 X-X' is shown in Figure 1. Modified after Fisk., 1947. 4 Stratigraphic section through flood basin deposits in the 12 Atchafalaya Basin. Data from Krinitzsky and Smith, 1969. 5 Cross-section through the meander belt near False River. 14 Modified after Saucier, 1969. The position of Profile Y-Y' is shown in Figure 2. 6 Distribution of sub-environments in the False River 15 Region. Modified after Saucier (1969) and Fisk, 1947. 7 Schematic cross-section through a Mississippi River 19 point bar showing relationship between upper and lower point bar sub-environments. 8 Topography of the concave bench. 22 9 Origin of concave benches. 23 10 Meandering history of the Mississippi River in the False 26 River Region. 11 Composite section (schematic) through a Mississippi River 32 point bar showing fining-upward sequence and relationship between upper and lower point bar sub-environments. viii 12 Diagram showing dimensions of large-scale trough cross- 33 stratification in lower point bar deposits at the Old River Locksite. Modified after Frazier and Osanik, 1967. 13 Origin of lower point bar stratification. 35 14 Stratification in upper point bar ridge deposits. 37 15 Trench data from upper point bar deposits at Solitude 39 Point.